Cutting head, rotary tool and support for the rotary tool and for the accommodation of the cutting head

ABSTRACT

A cutting head is formed for insertion into a support in a modular rotary tool, in particular a drill. It has a coupling pin onto which outer cover surfaces and torque surfaces are formed as clamping surfaces. The coupling pin has a particular circular groove, which divides the cutting head into a front pin part and a rear pin part. Stop surfaces for an axial pullout safety are formed in the transition area between the two parts. The torque surfaces and the clamping surfaces are arranged in different pin parts. The torque surfaces are preferably formed in the rear pin part.

FIELD OF THE INVENTION

The invention relates to a rotary tool, in particular a drill, with sucha cutting head, as well as a support for such a rotary tool and foraccommodating the cutting head.

BACKGROUND OF THE INVENTION

Drills having replaceable cutting tips mounted on shanks are known. Thecutting heads and shanks display continuous and complementingconfiguration as fluted drills. To this end, each shank has structurefor retaining and rotating an associated cutting head. The associatedcutting head has complementing structure for being retained and rotatedby the shank. While these devices will operate under some circumstances,closer analysis reveals that their useful lives are potentially undulylimited. More specifically, the retaining and drive structure of theshank is subject to deformation and failure during its service life dueto concentration of stresses imposed during when drilling on uneven orangled surfaces.

A conventional cutting head and a rotary tool can be derived, forexample, from WO 2008/072840 A2 or from the applicant's applicationsPCT/EP 2015/056288 or DE 10 2015 211744.8, which were unpublished as ofthe filing date.

The rotary tool is a so-called “modular” rotary tool, which extends inthe axial direction along an axis of rotation and has two couplingparts, namely a support and a cutting head. The cutting head isinterchangeably mounted on the support. To that end, the supporttypically has on its front side two fastening bars that face each otherand are separated by clamping slots that limit accommodation of pins.Inserted into this pin hole is a coupling pin of the cutting head. Thisis accomplished by rotating the cutting head around the axis of rotationin relation to the support. This rotation typically forms a clampingconnection between the cutting head and the support, clamping togetherthe two coupling parts. At the same time, no other fastening elements,for example screws or the like, are arranged. The fastening by clampingis accomplished between the outer cover surfaces of the coupling pin andthe inner cover surfaces of the pin hole.

Also arranged are two corresponding surfaces for transmitting torquefrom the support to the cutting head. These torque driving surfaces arereferred to below in brief as torque surfaces.

Another similar modular rotary tool can be derived from DE 10 2012 200690 A1.

Modular rotary tools can be divided into two different types. In a firsttype, like the one derived from, for example, WO 2008/072840 A2, thetorque surfaces extend outward radially up to an outermost periphery ofthe cutting head, also called “drill ridges.” According to a secondvariant, like the one described, for example, in the two unpublishedapplications cited above or also in DE 10 2012 200 690 A1, the torquesurfaces are formed directly on the coupling pin as its cover surfaces,which interact with corresponding inner cover surfaces of the fasteningbars.

Both the torque surfaces and the clamping surfaces of the cutting headand of the support are installed in pairs opposite each other in acoupled state when the cutting head is thus inserted into the support.At the same time, the corresponding clamping surfaces form in eachinstance a press fit; i.e., in the area of the clamping surfaces, thecoupling pin has an allowance vis-à-vis the pin hole.

In some of the applications cited above, formed for an axial pulloutsafety on each coupling pin are roughly horizontal stop surfaces thatinteract with corresponding stop surfaces of the support, in order tothus guarantee a positive fit in the axial direction for the cuttinghead. This positive fit prevents the cutting head from being pulled outfrom the support in an axial direction, for example when the rotary toolis withdrawn from the drill hole after a drilling procedure.

In WO 2008/072840 A2, a circumferential groove in the form of a recessis formed to form this axial pullout safety on the coupling pin. In asimilar manner, in PCT/EP 2015/056288 or DE 10 2015 211744.8, the stopsurface is formed by radial grinding in the form of recesses.

In DE 10 2012 200 690 A1, on the other hand, the coupling pin is formedto form a rear grip for an axial, dovetail-type pullout safety.

SUMMARY OF THE INVENTION

Based on the above, the problem of the invention is to provide a cuttinghead, a modular rotary tool and a support, in which the differentfunctions of the torque drive, the fastening by clamps and the axialpullout safety are reliably realized.

According to the invention, the problem is solved by a cutting head withthe features of claim 1, by a rotary tool with the features of claim 19and by a support with the features of claim 23. Advantageousdevelopments are described in the dependent claims.

The preferred designs and advantages of the cutting head, rotary tooland support are in each instance alternatingly transferable.

The rotary tool is generally a so-called “modular” rotary tool thatextends in an axial direction along an axis of rotation and which hastwo coupling parts, namely the support and the cutting head, wherein thecutting head and the support can be interchangeably attached to oneanother.

In operation, the rotary tool rotates around the axis of rotation in thedirection of rotation or peripheral direction. The rotary tool is inparticular a drill; thus, the cutting head is in particular a drillhead. However, the invention is not limited to use with a drill. Therotary tool can also be, for example, a milling tool or another type ofrotating tool, for example a reamer or the like.

The cutting head generally has a front cutting part, to which a couplingpin is attached contrary to the axial direction. Typically formed on thecutting part are two main cutting edges that are connected to eachother, in particular in the center section, by means of a chisel edge.Attached to each main cutting edge contrary to an intended direction ofrotation is a free surface, which typically merges into a clamping slotassociated with the next main cutting edge.

For the interchangeable fastening of the cutting head, the front of thesupport generally has two opposite-facing fastening bars separated byclamping slots that limit a pin hole. The coupling pin of the cuttinghead can be inserted to clamp into this pin hole. Preferably, thecutting head is fastened exclusively by the fastening by clamps. Theinsertion is made by rotating the cutting head around the axis ofrotation in relation to the support. This forms the desired clampingconnection between the cutting head and the support, so that the twocoupling parts are held together by clamping.

The pin hole of the support has inner cover surfaces and the couplingpin of the cutting head has outer cover surfaces that mutually interactwith one another. Formed on each inner cover surface and each outercover surface are corresponding torque surfaces for transmitting torqueon one side and corresponding clamping surfaces for transmitting aradial clamping force on the other side. These associated surfaces lieagainst each other in pairs in the connected state. The torque surfacesand the clamping surfaces form function surfaces for the functions oftransmitting torque and of clamping.

Also formed for an axial pullout safety are stop surfaces thatcorrespond to the pin hole and to the coupling pin, which are effectivein the axial direction for an axial pullout safety; i.e., in the joinedstate they are positively covered in the axial direction. In the case ofthe coupling pin, the stop surfaces are realized by a groove that at thesame time divides the coupling pin into a front pin part formed by thegroove and a rear pin part. To form the groove, during manufacture inparticular with a grinding wheel, an indentation extending in a radialdirection is made by grinding. Thus as a result of the groove, aquasi-section is formed between the two pin parts, forming the stopsurface.

For the support, to form the stop surfaces an overhang is formed thatcorresponds to each fastening bar, which overhang in the joined statethus overlaps the rear pin part and engages the groove. Corresponding tothe coupling pin, the pin hole also has a front receiving part and arear receiving part.

The terms “front” and “rear” refer to the axial direction. The axialdirection extends in the direction from the support up to the cuttinghead. The “front” means the part in the direction of the cutting headand the “rear” means the part in the direction of the support.

The function surfaces are generally formed on the outer cover surfacesof the coupling pins or on the inner cover surfaces of the pin hole. Thecoupling is a type of coupling in which the torque transmission surfacesare arranged on the interior side; i.e., they are hemmed in on theperiphery by the fastening bars. The torque surfaces thus specificallydo not extend to the outermost periphery of the cutting head; i.e., notup to the rear of the rotary tool, which typically forms theperiphery-side boundary surface of the rotary tool.

At least one type of function surfaces, in particular the torquesurface, is formed on the rear pin part. Because this rear pin part hasa greater diameter than the groove, the rear pin part is more stable andbecause of its greater radial extension, it is also better suited forthe transmission of forces.

An appropriate further development also provides that the functionsurfaces, i.e. the torque surfaces and the clamping surfaces, aredivided between the two parts (pin parts and receiving parts). As aresult, different functional levels are defined on the coupling, so thatthe top pin part or receiving part defines one functional level and thebottom pin part or receiving part defines the other functional level.This divides the functions of torque drive and clamping into differentaxial subsections. This has the particular advantage that thecorresponding sections of the coupling pins and of the pin hole can beoptimized for the individual functions. In addition, the axial pulloutsafety is also realized by the stop surface, which quasi-separates thetwo parts, regardless of the functions of torque drive and clamping.Altogether, this results in a coupling optimized with regard todifferent functions, which allows the various functions to be optimizedto the different sections.

According to one suitable design, the torque surfaces are formed on thebottom pin part and receiving part, respectively. Because the top parthas the groove and/or is formed by the groove, the bottom part generallyextends more in the radial direction. Because the greatest possibleradial extension is advantageous for transmission of torque, thisguarantees an especially effective transmission of torque.

The axial length of the front pin part preferably corresponds to theaxial length of the groove; i.e., no other section of the coupling pinconnects to the groove in an axial direction. The transmission areasbetween the individual functional levels typically merge into oneanother across at least rounded corner areas. Thus, the cutting part,which in the radial direction juts over the coupling pin while forming ahead-bearing surface, connects directly onto the groove forward in theaxial direction. Thus in particular, the groove merges into a roundingin the head-bearing surface. On the opposite side, the groove preferablyalso merges into the stop surface via a curve. Each stop surface in turnpreferably also passes over a curve or via a chamfer in the lateralsurface of the rear pin part. The rear pin part is in turn limited by abottom pin base, which preferably is formed by a horizontal surface. Thelateral surface of the rear pin part preferably also passes over a curveor a chamfer in the pin base.

In one suitable design, the groove runs in a peripheral direction andthus transverse to the axial direction. Thus, it is not inclined withregard to the axial direction and in particular does not have a helicalshape.

The groove suitably extends in a peripheral direction around the entirecoupling pin, except for any recesses caused by clamping slots, whichare formed in the cutting head and cut the coupling pin. In onepreferred embodiment, clamping slots are formed, namely in the cuttinghead, which are aligned with clamping slots of the support. Theseclamping slots also typically extend into the coupling pin, thus cuttingthem.

As a result of the fully circular groove, corresponding stopsurfaces—except for interruptions caused by the clamping slots—arepreferably fully circular also. Thus, the stop surfaces run along sidesof the support over the entire fastening bar. The two fastening bars areseparated from each other on the support side by the clamping slots.

Alternatively, the groove only runs over a partial area of the fasteningbars and thus also only over a partial area of the coupling pin.Preferably, the stop surface joins the torque surfaces in a peripheraldirection.

In the inserted state, it is not absolutely necessary that thecorresponding stop surfaces directly abut one another or are evenclamped together. In principle, a slight gap between the stop surfacesis possible. The pullout safety formed by the stop surfaces is intended,when the rotary tool withdraws, for example, from a bore hole, toprevent the cutting head from being pulled out from the support.

In one preferred embodiment, the stop surface preferably extendsaccording to a first embodiment perpendicularly in the axial directionand thus in the horizontal direction. Thus, the stop surfaces form acommon horizontal plane inside of which the stop surfaces are arranged.

Alternatively, the stop surfaces are preferably arranged at an inclineto the axial direction. In general, the stop surfaces are spread out bya direction along the periphery of the coupling pins and in a transversedirection. The transverse direction runs outward from the axis ofrotation in the direction of the periphery. This transverse direction isinclined under the first angle of inclination with regard to the axialdirection. The first angle of inclination is specifically not 90°; i.e.,the transverse direction and thus the stop surfaces do not runperpendicular to the axial direction.

The first angle of inclination preferably ranges from 30° to 85° and inparticular ranges from 50° to 75°. Accordingly, the stop surface is thusinclined opposite a horizontal plane at an angle from 5° to 60° and inparticular at an angle from 40° to 15°. Correspondingly, thesupport-side stop surface is also inclined at the same angle ofinclination, so that the corresponding stop surfaces run parallel to oneanother. The inclination of these stop surfaces is technically favorablefor manufacture. To connect the groove to the coupling pin, typically agrinding wheel is used. Grinding the groove simultaneously forms thestop surfaces. The short axial length of the groove makes it necessaryto use comparatively thin grinding wheels. The position of inclinationmakes it possible to use thicker grinding wheels.

At least one type of function surface on the cover side, and preferablyboth types of function surfaces on the cover side, run parallel to theaxial direction. In particular, the cover-side function surfaces do notform in the axial direction an effective pullout safety; i.e., none ofthe cover-side function surfaces is inclined in such a way that apositive pullout safety is formed in the axial direction. Thus, viewedfrom the axial direction (seen from back to front), no cover is formedbetween the support-side and the cover-side function surfaces.

As an alternative to the design in which the two function surfaces runparallel to the axial direction, a type of cover-side function surfacesis inclined at a second angle of inclination with regard to the axialdirection. Each cover-side function surface is in turn spread out by adirection along the periphery and a longitudinal direction perpendicularto it. The longitudinal direction is aligned at the second angle ofinclination with regard to the axial direction. The second angle ofinclination preferably ranges from 10° to 45° and in particular rangesfrom 20° to 30°.

Preferably, this function surface is inclined in such a way that it isinclined contrary to the axial direction on the axis of rotation; i.e.,viewed in the axial direction, no positive pullout safety is formed withthe fastening bars.

This inclined function surface is preferably a torque surface. Incliningthe torque surface improves the force transmission between the couplingpins onto the fastening bars. The inclination transmits torque onto thesupport also in the axial direction. This reduces the load of thefastening bars in the transverse or radial direction. In combinationwith the arrangement of the torque surfaces in the rear part, this alsoguarantees an altogether reliable transmission of high torques.

Altogether, the coupling pin is preferably roughly rectangular and has apair of opposite-facing convex, i.e. outwardly curved, front sides aswell as a pair of opposite-facing long sides running specifically in astraight line. In one embodiment in which the pin is cut by clampingslots, each long side is interrupted by a respective clamping slot. Atthe same time, the clamping slots are in each instance arranged in aroughly diagonal manner and facing the coupling pin. The torque surfacesare also formed specifically on the longitudinal surfaces and theclamping surfaces are formed on the front sides. This rectangularembodiment with long sides that are oriented at an angle with regard tothe peripheral direction or direction of rotation of the rotary toolmakes possible effective transmission of torque across the long sides.

Advantageously, the two parts, i.e. the rear and the front top pin partor receiving part, extend in an axial direction, preferably over acomparable length. This makes the different functions available inroughly the same lengths for the function zones. “Comparable length”means in this connection that the lengths of the two parts differ by nomore than 30%, preferably by no more than 10%. Most preferably, they areidentical.

In one preferred embodiment, as an alternative to allocating thefunction surfaces to the two pin parts, both types of function surfacesare formed on the rear pin part. This makes possible a shorter pinlength or if the pin length is the same, a greater length of the rearpin part compared to allocating the two function surfaces to the two pinparts, because the groove can now be made much smaller. Therefore, inthis case the groove specifically and exclusively serves to form thestop surfaces.

Preferably, the groove length, i.e. the length of the groove in theaxial direction, is only 0.3 to 0.5 times the axial length of the pinpart.

The coupling pin generally has a pin length that extends from thealready mentioned head-bearing surface up to the pin base. Accordingly,the pin hole also has a length that is defined by the distance betweenthe front contact surfaces of the fastening bars and a base of the pinhole. According to a first preferred variant, the two lengths arecoordinated in such a way that in the joined state the head-bearingsurface of the cutting head rests on the front contact surfaces and aslight distance (gap) is formed between the base of the pin hole and thepin base. Thus, in this variant the pin length is shorter than thelength of the accommodation.

In a second preferred embodiment, in the combined state the coupling pinand its pin base are supported on the base of the mounting. Therefore,in this case the pin length is greater than the length of the mounting.In the second design variant, therefore, a slight gap is formed betweenthe front contact surfaces and the head contact.

The distance, i.e. the difference between the two lengths, is preferablyno more than in the range of less than one hundredth of a millimeter.However, in principle, a greater distance can be set.

In one suitable design, in each instance cut-outs are made on the baseof the pin hole in the transition area from the inner cover surfaces tothe base. In this connection, a “cut-out” means a kind of depression, sothat a hypothetical cutting plane of the base (extending in a horizontaldirection) is cut in the longitudinal direction (and thus at ahypothetical lengthening of the inner cover surface) of the bottomreceiving part of a clearance.

The clearance preferably extends from the start of the fastening barcontrary to the direction of rotation. In so doing, the clearance formsa radius. The clearance reduces in an advantageous manner stresses thatoccur at the inserted cutting head. The clearance has a positive effecton the elasticity of the fastening bars.

According to a first design variant, the clearance only extends over apartial section of the fastening bar and, indeed, in particular onlyover the area of the clamping surfaces. Alternatively, the clearance ina suitable alternative extends over the entire fastening bar.

As a result of the coupling pins, generally a good guide is formed, inparticular for forces having a lateral effect on the cutting head, forexample in the case of a slight tilting away from the axial direction.At the same time, the coupling pins prevent any tilting of thelongitudinal axis of the cutting head in relation to the longitudinalaxis of the support.

According to a preferred further development, the coupling pins alsohave in the rear pin part, i.e. in the area of the torque surfaces,excess with regard to the pin hole. In the area of the clampingsurfaces, excess is realized for the desired clamping effect of thecoupling pins. Rotating the coupling pin therefore somewhat expands thepin hole. The additional excess is now also achieved in the rear pinpart, so that in the inserted state, there is no distance between thecoupling pins and the pin hole, or only a small (<5 μm) one. Thisguarantees a good guide.

Excess” generally means that a nominal width of a coupling pin isgreater than a corresponding nominal width of the pin hole. In the areaof the clamping surfaces, the excess ranges, for example—measured as thedistance from the clamping surface to the axis of rotation—from 2/100 to4/100 mm. The excess in the rear pin part is advantageously smaller thanin the front pin part, and in particular is smaller by at least a factorof 2 and preferably by a factor of 2 to 4.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the invention are described in detail by theuse of figures. In the figures, identically acting parts are given thesame reference numbers.

FIG. 1A is a perspective, exploded view of a section of a rotary toolwith a support and a cutting head according to a first design variant;

FIG. 1B is a perspective view of a section of the rotary tool accordingto FIG. 1A where the cutting head is inserted in the support;

FIG. 2A is a perspective view of the cutting head of the first designvariant;

FIG. 2B is a bottom-side view of the cutting head according to FIG. 2A;

FIGS. 2C, 2D are in each instance side views of the cutting headaccording to FIG. 2A rotated toward one another at 90°;

FIG. 3A is a perspective view of a support according to a first designvariant for accommodating the cutting head according to FIGS. 2A through2D for the rotary tool described in FIGS. 1A and 1B;

FIG. 3B is a top view of the support according to FIG. 3A;

FIG. 3C is a sectional view along lines of intersection C-C in FIG. 3B;

FIG. 3D is a top view of the support according to FIG. 3A;

FIG. 3E is a sectional view through the support according to sectionalline E-E in FIG. 3D;

FIG. 4A is a perspective view of the support according to a firstalternative with a partially extending clearance;

FIG. 4B is a perspective view of the support according to a secondalternative with a clearance that extends over an entire fastening bar;

FIG. 5A is a side view of a first embodiment, in which the coupling pinis shorter than the pin hole;

FIG. 5B is a side view of a second embodiment, in which the coupling pinis longer than the pin hole;

FIG. 6A is a perspective view of the cutting head of a second designvariant of the rotary tool;

FIG. 6B is a sectional view of the support of the second design variantfor accommodating the cutting head according to FIG. 6A;

FIG. 7A is a third variant of the rotation tool as shown in perspective;

FIG. 7B, C is a side view and a bottom-side top view of a cutting headof the third variant of the rotation tool according to FIG. 7A; and

FIG. 7D, E is a top view and a sectional view along the cutting line E-Ein FIG. 7D of the support of the third variant of the rotation toolaccording to FIG. 7A.

DETAILED DESCRIPTION OF THE INVENTION

The rotary tool 2 shown in the figures is formed as a modular drillingtool. It extends in an axial direction 4 along an axis of rotation 6.Around the axis of rotation 6 rotates the rotary tool 2 during normaloperation in the direction of rotation, which at the same time defines aperipheral direction 8.

The rotary tool 2 consists of a support 10 and a cutting head 12 thatcan be interchangeably fastened to it. The cutting head 12 has a frontcutting part 13 and a coupling pin 14 connected to it. The cutting part13 is limited on the front side by an anterior front surface and in thisinstance does not have precisely calculated main cutting edges, whichtypically are connected to one another in the center of a drill frontvia a transverse cut and extend radially outward. Main cutting edges areconnected to the main free areas on the front contrary to the directionof rotation and peripheral direction 8. On its circumference, thecutting head 12 has a ridge 15 that is interrupted by opposite-facingclamping slots 16 that start in the cutting head 12 and merge into thesupport 10. In the exemplary embodiment, the clamping slots 16 areroughly spiral in shape. The support 10 is a grooved shaft section inwhich secondary cutting edges, which extend, for example, along theclamping slots 16 and start at the cutting head 12, continue. Anon-grooved tightening section is typically attached to a grooved shaftsection of the support 10, with which the rotary tool 2 is clamped intoa machine tool.

Elements on the support 10 that correspond to one another are identifiedbelow with the letter “a” and on the cutting head 12 with the letter“b.”

The support 10 has on its front side two roughly diagonal,opposite-facing fastening bars 18 that are interrupted by the clampingslots 16. The fastening bars 18 extend in a peripheral direction 8 ineach instance across an angular range of approximately 70° to 90°. Thefront of each fastening bar 18 is limited by flat front contact surfaces22 a, which are arranged in the exemplary embodiment within a commonhorizontal plane to which the axis of rotation 6 is thus verticallyaligned.

The circumference of the pin hole 20 is limited by inner cover surfaces24 a of the fastening bars 18. It is also limited on its bottom side bya base 25 a running horizontally, i.e. perpendicular to the axis ofrotation 6. Inserted into this base 25 a concentric to the axis ofrotation 6 is a centering hole 26 a. Also running in the exemplaryembodiment 2 are coolant channels 28 in the support 10, which escapethrough the bottom surface and align there with corresponding coolantchannels 28 of the cutting head 12.

On the inner cover surfaces 24 a, the support 10 has in each instancetorque sections 30 a and clamping sections 32 a, which are aligned inthe axial direction 4 offset to one another and follow—viewed in aprojection in axial direction 4—one another in peripheral direction 8under an intermediate arrangement of a transition section. Directlyattached to the base 25 a are groove-like indentations 36 in the innercover surfaces 24 a, which forms a projection. This projection forms onits bottom side aligned to the indentation preferably horizontallyextending stop surfaces 38 a.

The groove-like indentation 36 formed as a type of recess divides thepin hole 20 into two parts, namely a front receiving part 40 a and arear receiving part 42 a.

Corresponding to the pin hole 20, the cutting head 12 has the couplingpin 14, which extends in axial direction 4. The coupling pin 14 isradially offset backwards in a radial direction from the peripheralsurfaces of the ridge 15. Corresponding to the pin hole 20, the couplingpin 40 has outer cover sections 24 b, on which also are formed torquesections 30 b and clamping sections 32 b. These sections are aligned inthe axial direction 4 offset to one another and follow—viewed in aprojection in axial direction 4—one another in peripheral direction 8under an intermediate arrangement of a transition section.

The radially offset backwards coupling pin 14 forms in the transitionsfrom the cutting part 13 to the coupling pin 14 a radial projection tothe ridge 14, as a result of which two head-bearing surfaces 22 b areformed that are in turn arranged in a common horizontal plane and whichare separated by the clamping slots 16.

Inserted into the coupling pin 14 is a particular—except for therecesses caused by the clamping slots 16—circumferential groove 37 thatdivides the coupling pin into two parts, namely a front pin part 40 band a rear pin part 42 b.

Also formed concentrically to the axis of rotation 6 on the coupling pin14 is an insertion pin 26 b, which is formed solely for use in thesupport 10 as a first centering aid of the cutting head 12. The cuttinghead 12 is actually centered by the clamping sections 32 a and b.

As is clear in particular from the top views of the cutting head 12according to FIG. 2A and the top view of the support 10 according toFIGS. 3A and 4A, the coupling pin 40 and the pin hole 20 are essentiallyrectangular and thus have a roughly block-like shape. The coupling pin14 therefore has, in particular, long sides extending in a straight lineand convex, curved front sides, except for, however, diagonal,opposite-facing areas of the long sides of the roughly square transversesection formed by the clamping slots 16. Formed on the long sides ornarrow sides of this roughly rectangular transverse section are thetorque sections 30 a and b, and formed on the front sides are theclamping sections 32 a and b. The clamping sections 32 a and b run—forexample viewed in a cross-section perpendicular to axial direction4—along a circular arc or along an elliptical arc. The corner areas ofthe roughly rectangular transverse section are rounded off.

In the exemplary embodiments, the groove 37 and the groove-likeindentation 36 in each instance extend completely circumferentially andin each instance lead into the clamping slots 16. The two parts (pinparts and receiving parts) 40 a and b and 42 a and b form two functionzones or functional levels that are offset to one another in axialdirection 4. In the front part 40 a and b are formed the clampingsurfaces 32 a and b, and in the rear part 42 a and b are formed thetorque surfaces 30 a and b.

As is clear in particular from the top views of FIGS. 2B and 3B, thetorque surfaces 30 a and b are formed on the long sides of theapproximately square basic geometry of the pin hole 20 and of thecoupling pin 14. The clamping surfaces 32 a and b are on the other handformed on the front sides of the square basic geometry.

The groove 37 passes—viewed in axial direction 4—on the end sidepreferably across rounded transition areas in the head-bearing surfaces22 b extending radially outwards and in the backward area passes intothe stop surfaces 38 b. The groove 37 has a groove length 11 that isdefined by the distance between the head-bearing surfaces 22 b and thestop surface 38 b. At the same time, the groove length 11 also definesin this respect an axial length of the front pin part 40 b. In the samemanner, the front receiving part 40 a also has a length corresponding tothe groove length 11.

The rear pin part 42 b extends in an axial direction across a partlength I2 that is defined by the distance between the stop surfaces 38 band the base 25 b. In the same manner, the rear receiving part 42 a hasa length corresponding to the part length I2.

The part length I2 and the groove length 11 are roughly the same, andpreferably identical. They preferably differ by no more than 30%. Theygenerally range, for example in the case of a rotation tool 2 with anominal diameter of 16 mm, between typically 2 mm and 5 mm, and inparticular measure approximately 3 mm (+/−0.5 mm). For other nominaldiameters, the respective part length is correspondingly adjusted sothat the ratio of nominal diameter to part or groove length remains thesame.

In the first exemplary embodiment according to FIGS. 1 through 4, boththe torque surfaces 30 a and b and the clamping surfaces 32 a and b runparallel to the axial direction. Thus, they are not inclined in relationto the axial direction. The stop surfaces 38 a and b preferably rununder a first angle of inclination α1 inclined in relation to axialdirection 4 (see FIG. 1A). The first angle of inclination α1 preferablyranges between 30° and 85° and in particular between 50° and 75°. In theexemplary embodiment it is at approximately 70°.

Alternatively, the stop surfaces 38 a and b run in a horizontaldirection perpendicular to the axial direction.

The stop surfaces 38 a and b are generally clamped by a direction alongthe circumference of the coupling pin 14 or of the pin hole 20 and atransverse direction that is aligned perpendicular to the directionalong the circumference. At the same time, this transverse direction isinclined with regard to axial direction 4 under the first angle ofinclination α1. If a circumferential section runs along a circular arcline around the axis of rotation 6, the transverse direction willcorrespond to the radial direction.

The stop surfaces 38 a and b extend in a longitudinal direction thattypically measures a few millimeters, for example 0.5 mm to 2 mm.

The transition areas between various lateral surfaces 30 a and b, 32 aand b in an axial direction to the adjacent surfaces 22 a and b, 38 aand b, and 25 a and b, are in each instance rounded or tapered.

FIGS. 4A and 4B show two alternatives for the support 10, in which aclearance 44 is formed in the transition area from the base 25 a to theinner cover surfaces 24 a of the bottom receiving part 42 a. To thatend, material in the corner and transition area is removed, for examplewith the help of a grinding wheel or milling head.

In the design variant according to FIG. 4A, the clearance 44, in thisinstance starting from the clamping slot 16, extends contrary torotation and peripheral direction 8 only across part of the respectivefastening bar 18, and indeed in particular across the area in which theclamping surfaces 32 a are formed. In contrast to this, the clearance 44in the design variant according to FIG. 4B extends across the entireangular range of the fastening bar 18, therefore extending from aclamping slot 16 up to the opposite-facing clamping slot.

FIGS. 5A and 5B show two different embodiments, in which the twocoupling parts (coupling pin 14, pin hole 20) in the joined statecontact the front or head-bearing surfaces 22 a and b (FIG. 5A) once andthe bottom surfaces (pin base 25 a, base 25 b, FIG. 5B) once. Bothembodiments can also be constructed like the first design variant.

A second design variant of the rotary tool 2 is shown in FIGS. 6A and6B. The basic difference with regard to the first design variantaccording to FIGS. 1A and 1B is that the rear pin part 42 b and the rearreceiving part 42 a are aligned together at an oblique incline withregard to axial direction 4; they taper off contrary to axial direction4. In addition, in the case of this design variant, no centering hole 26a or centering pin 26 b is shown. Otherwise, the second design variantcorresponds to the first design variant. With regard to thecorresponding features, please refer to the description of the firstdesign variant.

Due to the arrangement of the torque surfaces 30 a and b in the rearpart 42 a and b, the torque surfaces 30 a and b are aligned together atan oblique incline with regard to axial direction 4 under a second angleof inclination α2 (see FIG. 6B). This second angle of inclination α2preferably ranges from 10° to 45° and in particular ranges from 20° to30°. In the exemplary embodiment, it is approximately at 25°. Theoblique torque surfaces 30 a and b improve the transmission of force inaxial direction 4 into the support 10. The torque surfaces 30 a and band generally the inner cover surfaces 24 a are in general clamped by adirection along the circumference and a longitudinal direction alignedperpendicular to it. This longitudinal direction is aligned with regardto axial direction 4 under the second angle of inclination α2. If thesecond angle of inclination α2 is zero, the longitudinal direction runsparallel to the axial direction.

For assembling the cutting head 12, it first is inserted forward intothe pin hole 20 in axial direction 4 along with its coupling pin 14. Inthis connection, it is, in contrast to the position shown in FIGS. 1Aand 1B, rotated by approximately 90°. For this first axial insertion,the insertion pin 26 b provides a first centering support. Then, theentire cutting head 12 is rotated contrary to rotation and peripheraldirection 8 around the axis of rotation 6 within the pin hole 20. Inthis connection, the stop surfaces 38 a and b form a positive rear gripfor an axial pullout safety. The clamping sections 32 a and b also forma press fit and thus a clamp. In this connection, a radial clampingforce is applied to the clamping sections 32 a and b from the fasteningbars 18 onto the coupling pin 14. In the end position, the correspondingtorque sections 30 a and b also come to rest together. In operation,force applied from the support 10 is transmitted via the torque sections30 a and b onto the cutting head 12.

In the assembled end position, according to the first embodiment shownin FIG. 5A, the head-bearing surfaces 22 b lie flat on the front contactsurfaces 22 a. According to the second embodiment, the pin base 25 blies on the base 25 a. To that end, the coupling pin 14 has a pin lengthI3 and the pin hole 20 has a length I4 auf. In the first embodiment, thepin length I3 is shorter than the length I4. In the second embodiment,it is the reverse.

Altogether, an extremely reliable coupling between the cutting part 12and the support 10 is realized by the design described herein containingthe function surfaces separated into different axial function zones,namely torque surfaces 30 a and b and clamping surfaces 32 a and b, aswell as the separately formed axial pullout safety in the form of thestop surfaces 38 a and b.

A further, third design variant is shown in FIGS. 7A through 7E inwhich, in contrast to the preceding variants, both the torque surfaces30 a and b and clamping surfaces 32 a and b are formed on the rear pinpart 42 b or on the rear receiving part 42 a. These surfaces aretherefore arranged at the same axial height, but are offset to oneanother in the peripheral direction 8. The roughly rectangular tranversesection geometry is maintained in the design variants described above.The torque surfaces 30 b are thus adjusted to the front sides of thecoupling pin 14 on the longitudinal sides and to the clamping surfaces32 b.

In this design variant, the groove 37 has a significantly shorter groovelength 11 that preferably ranges from 0.3 to 0.5 times the part length12. Thus, the part length 12 is generally significantly greater (by atleast a factor of 2) than the groove length 11. This makes possible,compared to the preceding exemplary embodiments, on the one hand a shortpin length 13, or the part length, 12 and thus the length of thefunction surfaces 30 a and b and 32 a and b, can be increased. [000105]As in the preceding exemplary embodiments, the groove 37 connectsdirectly to the head-bearing surface 22 b. The stop surfaces 38 b inturn run perpendicular to the axial direction 4 or inclined in relationto it. The pin hole 20 is also formed in accordance with the design ofthe coupling pin 14.

The patents and publications referred to herein are hereby incorporatedby reference.

Having described presently preferred embodiments the invention may beotherwise embodied within the scope of the appended claims.

What is claimed is:
 1. A cutting head for a rotary tool extending in anaxial direction along an axis of rotation comprising a cutting part inan axial front area, to which is attached contrary to the axialdirection a coupling pin with an outer cover surface that runs in aperipheral direction; torque surfaces and clamping surfaces formed onthe outer cover surface; a groove inserted into the coupling pin suchthat forms a front pin part, a rear pin part when viewed in the axialdirection, and a stop surface for an axial pullout safety effective inthe axial direction, wherein at least one type of function surface isformed on the rear pin part.
 2. The cutting head according to claim 1,wherein the one type of function surfaces is formed on the front pinpart and the other type of function surfaces is formed on the rear pinpart.
 3. The cutting head according to claim 1, wherein the torquesurfaces are formed on the rear pin part.
 4. The cutting head accordingto claim 1, wherein the groove runs transverse to the axial direction.5. The cutting head according to claim 1, wherein the stop surface runsunder a first angle of inclination at an incline to the axial direction.6. The cutting head according to claim 5, wherein the first angle ofinclination ranges from 30° to 85°.
 7. The cutting head according toclaim 6, wherein the first angle of inclination ranges from 40° to 60°.8. The cutting head according to claim 1, wherein the stop surface runsin a circle, except for any interruption by a clamping slot surroundingthe coupling pin in a peripheral direction.
 9. The cutting headaccording to claim 1, wherein the at least one type of the functionsurface runs parallel to the axial direction.
 10. The cutting headaccording to claim 1, wherein two types of function surfaces runparallel to the axial direction.
 11. The cutting head according to claim1, wherein the one type of the function surfaces is at an incline to theaxial direction under a second angle of inclination.
 12. The cuttinghead according to claim 12, wherein the second angle of inclinationranges from 10° to 45° and in particular ranges from 20° to 30°.
 13. Thecutting head according to claim 1, wherein the one type of the functionsurface is inclined so as to be inclined against the axial directiononto the axis of rotation.
 14. The cutting head according to claim 1,wherein the one type of function surface is a torque surface.
 15. Thecutting head according to claim 1, wherein the coupling pin is square,with a convexly rounded front side and long sides running in a straightline, wherein each long side is preferably interrupted by a respectiveclamping slot and that the torque surfaces are formed on the long sidesand the clamping surfaces are formed on the front sides.
 16. The cuttinghead according to claim 1, wherein the two pin parts extend in an axialdirection across a comparable length.
 17. The cutting head according toclaim 1, wherein both types of function surfaces are formed on the rearpin part.
 18. The cutting head according to claim 17, wherein the groovehas a groove length and the rear pin part has a part length, wherein thegroove length ranges from 0.3 to 0.5 times the part length.
 19. A rotarytool extending in an axial direction along an axis of rotationcomprising two coupling parts including a support and a cutting head,the cutting head interchangeably fastened to the support, wherein thesupport has front-side fastening bars with inner cover surfaces, whichlimits a pin hole; a coupling pin of the cutting head can be clampedinto the pin hole by rotating the cutting head in relation to thesupport, and the coupling pin has outer cover surfaces; two differenttypes of corresponding function surfaces that lie opposite each other inpairs in the assembled state, namely torque surfaces for transmittingtorque, as well as clamping surfaces for transmitting a radial clampingforce formed on the inner cover surfaces and on the outer coversurfaces; a groove inserted into the coupling pin such that forms afront pin part, a rear pin part when viewed in the axial direction, anda stop surface for an axial pullout safety effective in the axialdirection, wherein at least one type of function surface is formed onthe rear pin part.
 20. The rotary tool according to claim 19, whereinthe one type of function surfaces is formed on the front receiving partand the other type of function surfaces is formed on the rear receivingpart.
 21. The rotary tool according to claim 19, wherein the fasteningbars are limited by a top front contact surface; and wherein the pinhole is limited by a base; and wherein the pin hole extends from thefront contact surfaces up to the base across a length; and wherein thecutting head has front cutting part attached to which is the couplingpin; and wherein a head-bearing surface formed in the transition to thecoupling pin; and wherein the coupling pin extends across a pin lengthfrom the head-bearing surface up to a pin base; and wherein the pinlength according to a first variant is longer than the length of the pinhole and the pin length according to a second variant is shorter thanthe length of the pin hole.
 22. The rotary tool according to claim 19,wherein the coupling pin has both in the area of the clamping surfacesand in the area of the torque surfaces an excess in relation to the pinhole, wherein the excess in the area of the torque surfaces is smallerthan the excess in the area of the torque surfaces.
 23. A support for arotary tool as recited in claim 19, which is formed for theaccommodation of a cutting head as recited in claim 1.